This is no wonder: when you search for "TEST", you will find everything containing "TEST", therefore "TEST2", "XTEST", "TESTX", etc.

If you want to find only specific lines you will have to enlarge your search pattern so much that it becomes distinct. In your case this could be done by including the ":", which seems to separate the first from the second part of the line. Searching for "TEST:" will only find the first line, not the others.